Superior sensing performance of multi-walled carbon nanotube-based electrodes to detect unconjugated bilirubin

Abstract

The direct electrochemical behaviour of bilirubin in the physio-pathological concentration range and at physiological pH was investigated by cyclic voltammetry. Nanostructured electrodes with a thin film of multi-walled carbon nanotubes exhibited a higher sensing performance than bare electrodes. The detection limit obtained with nanostructured electrodes (4.2 ± 0.1 μM) allows the detection of both normal and pathological levels of bilirubin. Due to its sparse solubility in aqueous solvents, in human fluids bilirubin is found in the form of soluble complex with albumin. Therefore, the nanostructured-sensor response was studied in presence of different concentrations of this protein. A signal weakening was observed with increasing concentrations of albumin due to the decrease of free bilirubin. Finally, bilirubin detection was tested at concentrations typical of newborn jaundice (200-500 μM) and in the presence of normal albumin levels. A detection limit of 9.4 ± 0.3 μM was identified. Since this value is below the minimum critical bilirubin concentration for newborns, our sensor, modified with a thin film of carbon nanotubes, could potentially be used for bilirubin detection in cases of newborn jaundice.

Electrochemical Sensor for Bilirubin Detection Using Screen Printed Electrodes Functionalized with Carbon Nanotubes and Graphene

“…A clear change in the morphology observed after electrochemical reduction suggests a successful reduction of -COOH, -OH, and oxygen functional groups. It is also evident from the cyclic voltammograms that are applied on the GO-SPE before and after electrochemical reduction ( Figure 3 A) that the reduction peak observed at −0.5 V (Vs. Ag/AgCl) corresponds to the electrochemical reduction of GO [ 25 ]. Furthermore, a stable redox peaks around +0.2 V was observed after 500 cycles.…”

“…Electrodes that are modified with nanomaterials, such as metal nanoparticles [ 19 ], nanostructural conducting polymers (molecularly imprinted polymer) [ 20 , 21 , 22 , 23 ], carbon nanotubes [ 24 , 25 ], graphene, and their composites [ 26 , 27 ] have been reported as BR sensors. Those nanomaterials are well known for their efficiency to improve the electrocatalytic performance of the sensors by increasing the effective surface area.…”

New Generation of Electrochemical Sensors Based on Multi-Walled Carbon Nanotubes

“…Using DPV and the developed sensor (HIV-p24/CTS/MWCNT/GCE), a low limit of detection (0.083 pg cm −3 ), good selectivity, repeatability, reproducibility, stability, and accuracy were reached for the proposed electroanalysis; validation was performed by comparative studies with enzyme-linked immunosorbent assay (ELISA). The outstanding ability of MWCNT-based electrochemical sensors to simulate redox reactions that occur in vivo has also been demonstrated with the electroanalysis of hemoglobin [43], amino acids [44], cholesterol [45], bilirubin [46], neurotransmitters, and related compounds [47][48][49], and even microorganisms [50], in mammalian fluid samples, achieving great results and contributing to the early diagnosis and treatment of several related diseases.…”

Fabrication of the Enzyme‐less Voltammetric Bilirubin Sensor Based on Sol‐gel Imprinted Polymer

“…Electrochemical sensors have ease, rapidity and sensitivity in comparison with other techniques and often do not need to complex pre-treatment of samples. There are three basic approaches in these methods: the first one is the direct oxidation of bilirubin at the electrode surface [18][19][20][21][22][23]. The second one is an enzymatic method that utilizes the bilirubin oxidase enzyme for electrochemical measurement of BR.…”